Crossovers without a sub? Marantz 1710

[milo bloom]

Hi, we just upgraded to a new receiver after many years and because we're in a condo we don't use a sub (just fronts, center and rears, so 5.0).

We're not getting much bass response even after letting the system do it's automated set up with the little microphone thing so I'm trying to adjust the crossover levels.
Can anyone suggest how to adjust these to get a little more bass out of our 5.0 system?

thanks